Re: [PATCH 7/7] dmaengine: omap-dma: Support for LinkedList transfer of slave_sg

Russell King - ARM Linux
2016-07-18T10:42:00Z

On Thu, Jul 14, 2016 at 03:42:42PM +0300, Peter Ujfalusi wrote:
> struct omap_desc {
> + struct omap_chan *c;
> struct virt_dma_desc vd;

No need for this. to_omap_dma_chan(foo->vd.tx.chan) will give you the
omap_chan for the descriptor. In any case, I question whether you
actually need this (see below.)

> + bool using_ll;
> enum dma_transfer_direction dir;
> dma_addr_t dev_addr;
>
> @@ -81,6 +109,9 @@ struct omap_desc {
> };
>
> enum {
> + CAPS_0_SUPPORT_LL123 = BIT(20), /* Linked List type1/2/3 */
> + CAPS_0_SUPPORT_LL4 = BIT(21), /* Linked List type4 */
> +
> CCR_FS = BIT(5),
> CCR_READ_PRIORITY = BIT(6),
> CCR_ENABLE = BIT(7),
> @@ -151,6 +182,19 @@ enum {
> CICR_SUPER_BLOCK_IE = BIT(14), /* OMAP2+ only */
>
> CLNK_CTRL_ENABLE_LNK = BIT(15),
> +
> + CDP_DST_VALID_INC = 0 << 0,
> + CDP_DST_VALID_RELOAD = 1 << 0,
> + CDP_DST_VALID_REUSE = 2 << 0,
> + CDP_SRC_VALID_INC = 0 << 2,
> + CDP_SRC_VALID_RELOAD = 1 << 2,
> + CDP_SRC_VALID_REUSE = 2 << 2,
> + CDP_NTYPE_TYPE1 = 1 << 4,
> + CDP_NTYPE_TYPE2 = 2 << 4,
> + CDP_NTYPE_TYPE3 = 3 << 4,
> + CDP_TMODE_NORMAL = 0 << 8,
> + CDP_TMODE_LLIST = 1 << 8,
> + CDP_FAST = BIT(10),
> };
>
> static const unsigned es_bytes[] = {
> @@ -180,7 +224,64 @@ static inline struct omap_desc *to_omap_dma_desc(struct dma_async_tx_descriptor
>
> static void omap_dma_desc_free(struct virt_dma_desc *vd)
> {
> - kfree(container_of(vd, struct omap_desc, vd));
> + struct omap_desc *d = container_of(vd, struct omap_desc, vd);

struct omap_desc *d = to_omap_dma_desc(&vd->tx);

works just as well, and looks much nicer, and follows the existing code
pattern.

> +
> + if (d->using_ll) {
> + struct omap_chan *c = d->c;
> + int i;
> +
> + for (i = 0; i < d->sglen; i++) {
> + if (d->sg[i].t2_desc)
> + dma_pool_free(c->desc_pool, d->sg[i].t2_desc,
> + d->sg[i].t2_desc_paddr);

Why do you need a per-channel pool of descriptors? Won't a per-device
descriptor pool be much better, and simplify the code here?

--
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